Effect of span 80 - tween 80 mixture compositions on the stability of sunflower oil-based emulsions

The study describes the effect of span 80-tween 80 surfactant mixtures on the stability of the sunflower oil based emulsions. The emulsification was carried out in various proportions of span 80-tween 80 mixtures so as to have a HLB range varying from 6.4 to 13.8. Attempts were made to prepare both W/O and O/W emulsions by using oil: water fractions at 4:1 and 1:4 ratios, respectively. The emulsions which were stable for 24 h, were further observed for 56 h to have an insight on their long-term stability. The emulsions which showed signs of destabilization, during the period of 24 h to 56 h, were analyzed microscopically and measuring pH to understand the mechanism of destabilization. The stable samples were thoroughly characterized by light microscopy, pH measurement and accelerated stability test by thermocycling method. The micrographs of the samples were analyzed using Image J and Vision Assistant softwares. All samples stable up to 24 h were found to be W/O emulsions by dye solubility test. The unstable and short-term stable samples indicated cracking and creaming/sedimentation, respectively, as the destabilization phenomena. The pH of the short-term stable samples decreased with time whereas the pH of the long-term stable samples was almost constant throughout the 56 h time period. The long-term stable emulsions did not show any change in the particle size along the time scale